Motech swap questions with Gen IV 480hp LS3 crate engine

highoctane

Caught the Bug
To start, my Jeep is a '15 with the 3.6/auto trans, and is not a daily driver. It gets used for both rock crawling and for driving ridiculously fast on rough trails/access roads in northern AZ. It's a heavy Jeep, major build specs are in my sig. I wanted to ask about the feasibility of using the GM 480hp LS3 crate engine with the Motech Gen IV LS swap kit. It has the GMPP LS Hot Cam in it and I believe that is the only difference compared to the standard 430hp LS3. It does have a rougher idle and I'm curious if you guys at Motech have been able to tune out much of the quirks that a cammed LS can have.

Some more general questions that are related to the swap. I've looked at the DIY swap kits on the Motech website, and the list of items that come in it. I'd be going with the Premium kit that comes with the xfer case adapter for the 6L80 and aluminum radiator. I'm also planning to do this swap in my garage. When using the LS3 crate engine, is there anything else besides the engine and transmission that I would need? I must use a Sport/Sahara 2.72:1 xfer case instead of my Rubicon 4:1 case correct? I'd like to be able to just use the Jeep JK engine accessories, from what I've read this can be done with the brackets you guys make right? For sourcing a 6L80 trans, do I need one from a car, 2wd truck or 4wd truck, or does it not matter? Is a majority of your newest harness plug and play or is there still a good bit of cutting and splicing that needs done?

Thanks for any help. Planning to accumulate all the parts over the summer months and do this swap later this fall.

 

tgoss

New member
When I spoke to them it sounded like due to the female output on the later transfer cases you are required to do an atlas II on a 13+my JK.

They can correct me if I'm wrong but I just looked at my email thread with them.

Really curious about the cammed tuning as an LS3 with a mild cam is a must for me when the time comes for this upgrade.
 

Exodus 4x4

Advertiser
I had this conversation with them this week. Your '15 accessories aren't going to work. You'll need 3.8 accessories or GM. It'm opting for the GM because of this.

The 6L80 doesn't matter, but I think it helps if it's 4wd. Call Lee at United Auto recyclers in Omaha. He'll get you set up and he's the one Robbie's going to recommend to you.


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scrhino

New member
The 430 has plenty of power. I've got a friend who did the bruiser 480 and had a few overheating issues that I'm sure motech can handle but I think bruiser has stopped those engine swaps.
 

NecessaryEvil

New member
I would imagine a mild cam should not be a problem for them or out on the trail. As far as I know your options are the atlas or Sahara transfer case because of the transmissions output shaft. Also I believe the only difference between the 2wd and 4wd trans is the output shaft housing and you would need the obvious 4wd version. I just recently talked to Motech and they recommend the transmission to match the year of the motor. Hopefully any of my rambling helped.


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highoctane

Caught the Bug
When I spoke to them it sounded like due to the female output on the later transfer cases you are required to do an atlas II on a 13+my JK.

If that's the case I'm not sure why you couldn't just use a '13 + Sport/Sahara xfer case and swap the input shaft.


I had this conversation with them this week. Your '15 accessories aren't going to work. You'll need 3.8 accessories or GM. It'm opting for the GM because of this.

The 6L80 doesn't matter, but I think it helps if it's 4wd. Call Lee at United Auto recyclers in Omaha. He'll get you set up and he's the one Robbie's going to recommend to you.

That sucks about the engine accessories. Sounds like I'll have to plan on GM Camaro LS3 accessory drive then.

I'll have to get in contact with that auto salvage yard and see what they have. Thanks! [emoji106]


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Exodus 4x4

Advertiser
I'll have to get in contact with that auto salvage yard and see what they have. Thanks! [emoji106]



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Mine showed up yesterday, about a week after I called them. I feel like a got a great price on a low mileage transmission. IMO it helps to deal with the same people that Motech does.

As far as accessories go, Robbie said the GM parts are cheaper and better anyways. I was already leaning this way since it will obviously be easier to resell the 3.6 intact and the engine is just that less "frankensteined".


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MOTECH

New member
To start, my Jeep is a '15 with the 3.6/auto trans, and is not a daily driver. It gets used for both rock crawling and for driving ridiculously fast on rough trails/access roads in northern AZ. It's a heavy Jeep, major build specs are in my sig. I wanted to ask about the feasibility of using the GM 480hp LS3 crate engine with the Motech Gen IV LS swap kit. It has the GMPP LS Hot Cam in it and I believe that is the only difference compared to the standard 430hp LS3. It does have a rougher idle and I'm curious if you guys at Motech have been able to tune out much of the quirks that a cammed LS can have.

Some more general questions that are related to the swap. I've looked at the DIY swap kits on the Motech website, and the list of items that come in it. I'd be going with the Premium kit that comes with the xfer case adapter for the 6L80 and aluminum radiator. I'm also planning to do this swap in my garage. When using the LS3 crate engine, is there anything else besides the engine and transmission that I would need? I must use a Sport/Sahara 2.72:1 xfer case instead of my Rubicon 4:1 case correct? I'd like to be able to just use the Jeep JK engine accessories, from what I've read this can be done with the brackets you guys make right? For sourcing a 6L80 trans, do I need one from a car, 2wd truck or 4wd truck, or does it not matter? Is a majority of your newest harness plug and play or is there still a good bit of cutting and splicing that needs done?

Thanks for any help. Planning to accumulate all the parts over the summer months and do this swap later this fall.

The LS3 430 HP engine has good power and drivability. With a few small tune and exhaust changes we are seeing 450 HP at the crank. The advantage the 430 HP engine has over the 495(GM now rates the 480 at 495) is perfect drivability. An LS3 430 HP engine will idle all day on the trail, your wife will be comfortable driving it to the store; it is very much a Dr. Jekyll and Mr. Hyde engine. Mild like a stock engine but comes alive when you get on it. The Hemi and 495 engines feel more pumped up, like a muscle car they never quite relax. You get some rump, rump, rump and HC's at idle. I will say over the years we have an excellent 495 tune that idles well and still runs to 7,000 rpm, it's just not as relaxed as the 430 engine which runs like an Escalade.

You will want to loosen up your torque converter with the 480 HP engine and go to 2 1/2" exhaust. Run high performance converters the 495 engine has high cylinder pressures and will blow out standard cats.

Our new JK billet drive is pretty awesome, it uses the stock 2007-11 JK accessories and puts them back where they were so the original lines, hoses and connectors work. The Pentstar has an odd accessory drive that mounts the alternator backwards, we do use the Pentstar PS pump an compressor in some applications though.

If running the GM CTV accessory drive on an LS3 we find the stock Camaro PS pump works fine with tirews up to 37". For larger tires or hydraulics the Camaro pump does not work well and we have some options including substituting it for a JK or PSC pump while maintaining the stock head mount reservoir. Make sure if running the JK PS pump you run ATF4+ and if running PSC or GM use the mineral based PS fluid, we like the stuff GM sells.

Basically you can run a 241J from any 2007-11' JK manual or automatic. You can run a 241J from a MANUAL JK from 2007-16'. The automatic JK went to a female input on the TC in 2012 so both the automatic J and OR will not mate to the 6l80. We find the 4:1 OR low ratio is too low for general wheeling when combined with the 4:1 first gear of the 6l80. This is a 16:1 low ratio where a stock Rubicon(2007-11) is 11:1. Ironically when you mate a 2.7 241J to a 4:1 6l80 you end up with virtually the same low ratio as a stock Rubicon and it works perfect. You can get wheel speed up with the J TC for mud, sand and snow where the 4 and 5:1 ratios are better suited for serious crawling and will not work well on trails. With our 241J-6l80 adapter the 241 will handle 500 HP. The 241J is chain driven and has an internal oil pump so it is great on the highway and quiet. With a gear driven TC like the Atlas you need to be careful with proper set up and gear lube. Running a gear driven TC with thick oil behind a 4 cylinder CJ is very different than cruising 80 mph for hours in a 400 HP V8 and a 6,000 pound JK. Clearances and splash oiling must be right and unlocking hubs are desirable. We find the low cost solution the best, 241J with a 6l80. I also really like the Atlas 2 for 2WD low to free up the steering wheel and front wheel drive for snow. The 4:1 front planetary of the early JK's is relatively weak and I would not run it behind a 500 HP LS. I have seen the smaller output shafts of the 4l65's twist off even with 6 liter engines. The 6l80 runs a larger output and once our input gear is installed it's unlikely you will have any issues.

You can run a 6l80 from a 2WD, 4WD or an AWD vehicle. If running a 2WD 6l80 you need to cut off the output shaft and install some seals. We also support the 6l90 but prefer the 6l80. The 6l90 is longer than the 6l80 and has a larger output shaft. The 2 and 4WD 6l90's have different output shafts so the 2WD 6l90 will not work unless you replace it which is a PITA. Stick with a 6l80 if you can.

It's very important you match the transmission and engine. These CAN transmissions have TCM's built in. In general there are three groups of TCM's.

2007-8 will support basically only the early L92 6.2 from Escalade's and Denali's.
2009 a year all by itself and the 2009 6l80 will work in most 2009 engines. The 5.3 got the 6l80 in 2009.
2010+ this is what yoiu want. In 2010 GM increased compatibility between ECM's and TCM's across the board. So if you have a 2012 LS3 you can run pretty much any 2010-16' 6l80 2WD, 4WD or AWD.

https://www.youtube.com/watch?v=8U9zidtjB68
 

highoctane

Caught the Bug
Thanks Motech for the info! Will help me to start sourcing a xfer case and transmission. I'll likely get the crate engine from Summit Racing and just buy GM front engine accessories from a parts store or dealership. I already have PSC hydraulic assist on my 3.6 JK with the PSC pump. Sounds like your saying I have the option to use that pump with the GM accessories? I have 40s so the camaro pump wouldn't be up to the task.


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scrhino

New member
Thanks Motech for the info! Will help me to start sourcing a xfer case and transmission. I'll likely get the crate engine from Summit Racing and just buy GM front engine accessories from a parts store or dealership. I already have PSC hydraulic assist on my 3.6 JK with the PSC pump. Sounds like your saying I have the option to use that pump with the GM accessories? I have 40s so the camaro pump wouldn't be up to the task.


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So curious if you're still looking at the 480/495?
 

MOTECH

New member
Thanks Motech for the info! Will help me to start sourcing a xfer case and transmission. I'll likely get the crate engine from Summit Racing and just buy GM front engine accessories from a parts store or dealership. I already have PSC hydraulic assist on my 3.6 JK with the PSC pump. Sounds like your saying I have the option to use that pump with the GM accessories? I have 40s so the camaro pump wouldn't be up to the task.


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We can fit the early PSC JK pump to the CTV drive, we have a small bracket that allows you to use the stock Camaro reservoir.
 

BigPrince

New member
You'll love it. If you keep your 5.38s, you'll probably never downshift from 6th gear on the highway.

With the proposed engine/trans in this thread (430/495 6l80), what gearing does Motech recommend for Atlas TC and axles? I have 5.38 in my axles and a 4.3 Atlas II currently in my 2014 3.6l. Wondering if it would be worthwhile sending to AA to redo the current Atlas or buy new. Anyone run a 4speed? I also have a PSC pump/hydro assist already and appreciate the early info.
 

scrhino

New member
With the proposed engine/trans in this thread (430/495 6l80), what gearing does Motech recommend for Atlas TC and axles? I have 5.38 in my axles and a 4.3 Atlas II currently in my 2014 3.6l. Wondering if it would be worthwhile sending to AA to redo the current Atlas or buy new. Anyone run a 4speed? I also have a PSC pump/hydro assist already and appreciate the early info.

I guess you're running 40s. Eddie is running 5.38s w/ a 3.0 Atlas which you probably would want to go that route. And 4 speed would be unnecessary. I'll be running 60/80 axles next month but with 4.88s and a 3.8 Atlas. Plus I'm running 37s. I'll be running a little bit slow with 3.8 but I'm currently running 2.72 which to me is a little fast. Hope I'll be happy.
 

MOTECH

New member
With the proposed engine/trans in this thread (430/495 6l80), what gearing does Motech recommend for Atlas TC and axles? I have 5.38 in my axles and a 4.3 Atlas II currently in my 2014 3.6l. Wondering if it would be worthwhile sending to AA to redo the current Atlas or buy new. Anyone run a 4speed? I also have a PSC pump/hydro assist already and appreciate the early info.

TBH I like the LS3 430, I prefer the drivability over the 480 HP engine. We find the LS3 430 HP engine has about 450 HP at the crank and will outperform a stock 6.4 Hemi when running a 6l80 transmission.

The 6l80 is a strong transmission and it is unlikely you will break it even with a supercharged LS, we have run them in 700 HP engines with no problem. Our 6l80-241J TC adapter is good to 500 HP, we have many running behind the 495 engine. The Atlas 2 is a good choice if you need it - 2WD low and front wheel drive. If you don't need an A2 the 241J works great. I do not recommend(and neither does Advance) the Atlas 4 or the 241OR TC, they don't deal well with the torque. We also support the 6l90 transmission but realistically I would not run a 6l90
unless I already had one.

Stock 44 axles can hold up well with a 6.2 engine with tires under 37", if your running larger than 37's you want to beef up your stock axles or go with some 60's or... I like the D80 rear and D60 front combination. I have 80,000 miles on my stock 44's with a 6.2 with no issues because I drive conservative and that is what matters, you can break axles with a 3.8 in low range if you drive like a gorilla. But for the most part if running a 6.2 with 40's beef up the axles, if running 35" or smaller tires you can get away with the stock axles.

We have recommended gearing and you shouldn't gear an LS like a Hemi or V6. The diverse gearing of the 6l80 means you can launch hard with a 4:1 first gear and cruise at low rpm with a 2cd OD of .66. This means you can run 37's on 4:10's and still get reasonable performance. For general driving(both off road and highway) we like to shoot for a 2,000 rpm cruise speed at 70 mph. This gives you good off road performance with a 3:1 TC and good economy on the highway. So for general guidelines:

35's - 4:10's
37's - 4:56's
40's - 5:13's.

Now the LS is tolerant to gearing due to the 6l80 transmission and lots of torque. If towing or you live in the mountains of Colorado go up one gear size, so 4:88's with 37's instead of 4:56's. If you do mostly highway driving go down one gear size, so 4:10's with 37's instead of 4:56's. Do not go too low on the TC ratio unless you have a need. A 3.8, 4 or 5:1 TC is great on a rock but sucks on trails. With a 4:1 TC your screaming the engine in 6th gear to go 15 mph down a trail and with the torque of the LS you don't need to do that.
 

BigPrince

New member
I guess you're running 40s. Eddie is running 5.38s w/ a 3.0 Atlas which you probably would want to go that route. And 4 speed would be unnecessary. I'll be running 60/80 axles next month but with 4.88s and a 3.8 Atlas. Plus I'm running 37s. I'll be running a little bit slow with 3.8 but I'm currently running 2.72 which to me is a little fast. Hope I'll be happy.

I'm running 60 front, Sterling rear, and 41.5" Pitbulls. For the crawling we do, I would like to run the numbers on a 4 speed if the computer doesn't have a problem with it(?).

Eddie has a different primary use case being in Nevada. You're from Auburn - ever go to Chocco? The guys I've seen do Boatramp have been ultra low geared going slow and I've seen bouncers throw big HP at it and not make it.

Motech - thanks for the overview. Sounds like both of y'all agree 5.38s would be ok, if a little torquey, with 40-42s. I may just want to swap out or regear(if possible) the Atlas. Figured I would need to change the input, maybe just do that and see how much I like/hate it and go from there when the time for the conversion comes.

Thanks!
 

highoctane

Caught the Bug
I live at nearly 6k feet in northern AZ, and frequently drive long, steep mountain grades on I17 in AZ, so I'll for sure be staying with the 5.38 gears in my Dynatrac axles. By swapping in the 241J with the 2.72:1 low range I'll be just fine offroad. If I ever break the xfer case or adapter I'll go to an Atlas II.


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